As bushfire smoke can cover very large areas, including major cities, it has the potential to affect millions of people and is a significant public health problem.

We know that healthy people tolerate brief episodes of smoke exposure quite well, but those with pre-existing heart or lung disease, pregnant women, young children, and the elderly are more likely to be affected by smoke.

Bushfire Smoke consists of a very complex mixture of particles and gases, including carbon monoxide, nitrogen oxides, and volatile organic compounds. And increased concentrations of the secondary pollutant ozone have been noted during large fires.

On the population level, the major concern is the very small particles or PM2.5 – particles with an aerodynamic diameter smaller than 2.5 micrometres (µm) – that can penetrate deep into the lungs. These small particles in urban air have shown to have an effect on respiratory and cardiovascular health, even at concentrations well below the current air quality standards in Australia.

This naturally poses the question of what their health effects could be during bushfires, when their concentrations are many times higher and regularly exceed the air quality standards.

At a global scale, our team has estimated that around 340,000 premature deaths each year can be attributed to smoke from landscape fires. We have previously shown that on days when severe smoke plumes affected Sydney’s air quality, deaths increased by around 5% and hospital admissions for lung problems increased even more.

There are several measures that you can take to reduce your exposure to the bushfire smoke.

  • If the pollution is severe in your local area, people at particularly high risk should consider the practicalities of leaving the affected area until the air quality has improved.
  • Stay indoors and close windows and doors. If you have a well-sealed house this can delay the entry of smoke particles into your home, but it is only a temporary measure and completely depends on the structure of the house. If the house is not well sealed, smoke particles indoors will rapidly equilibrate with outdoor levels.
  • Avoid exercise, as this results in faster and deeper breathing and can increase your exposure to smoke up to tenfold.
  • If you have an air conditioner, set it to recycle so you don’t bring in outdoor air. If you have the option of adding a filter to your air conditioner, do so.
  • Apart from reducing your exposure to smoke, it’s important if you have a heart or lung condition that you have your medication and follow your treatment plan. People with asthma, for instance, should make sure they have a current asthma action plan and keep their blue reliever medication handy.